In the previous grant period, we sought to identify a mechanistic link between two major themes in the pathogenesis of Alzheimer[unreadable]s Disease: oxidative stress and amyloid fibril formation. Our efforts have led to the discovery of a remarkable chemical amplification mechanism by which oxidatively damaged lipid membranes accelerate fibril formation by amyloid [unreadable] proteins. This mechanism operates at physiologically plausible concentrations in vitro, and it causes rapid fibril formation in circumstances where it would otherwise occur slowly or not at all. We are now proposing biochemical and biophysical studies with a translational focus to follow up on the discovery of this mechanism and ascertain its significance to the pathogenesis of AD. This proposal includes (a) in vitro studies to ascertain specific chemical details about this amplification mechanism that remain undefined, (b) postmortem studies of human brain tissue to demonstrate that this mechanism is associated with amyloid plaque formation, and (c) in vivo studies of transgenic mice to establish the link between oxidative lipid degradation products and amyloid formation in a system that is amenable to experimental therapeutic intervention. The chief technologies to be employed are a form of internal reflection infrared spectroscopy developed in and unique to this lab, quantitative mass spectrometry, and sequencing mass spectrometry.